Field of the Invention
This invention relates to a control valve unit configured to control oil flow to an automatic transmission.
Description of the Related Art
Conventionally, there is a known control valve unit of this type, in which a check valve mechanism is incorporated in the control valve unit. For example, Japanese Unexamined Utility Model Publication No. 63-094348 (JPS63-094348U) describes a control valve unit having a pair of bodies, a separator plate interposed between the pair of bodies, and a plug fitted into an opening of the separator plate. The plug is provided with a valve port and a valve seat, and the valve port is open and closed by applying hydraulic force to contact and separate a check ball with and from the valve seat.
However, owing to the plug being fitted into the opening of the separator plate in the control valve unit described in JPS63-094348U, cracking, deformation or the like is apt to occur at the fitted portions of the separator plate and the plug. A control valve unit that optimally incorporates a check valve mechanism without risk of incurring cracking, deformation and the like is therefore desirable.